Posts

Mini work-bench

I started writing this ages ago, during lock-down. A second lock-down seems imminent now, so I may as well publish it anyway. In any case I did make something, which I'm now looking to make more flexible, and reading this again will remind me of my original ideas. At the timer there was s a bit of a fad on you-tube: the mini work-bench: Pask Makes Adrian Preda Laura Kampf The circumstances made these really attractive. I guess, hence the fad. This would likely work for me later too: I would generally have a really small workspace, where I have a desk, where I might sit down and solder, etc, and I would get this out on the desk to do wood working. However, I don't have access to most of the facilities I need to build one. It would be vastly better to buy something, however all I've found is this which is small and rather expensive. So the question is how to make something with a small set of hand tools at my disposal... These either use, or make enormous block
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FLSUN Q5

So I ended up buying an FLSUN Q5. I've assembled it, and done a test print. I spent perhaps an hour assembling it and setting it up, but my daughter helped for the second half. It was really very easy, but it helped hugely to have watched someone else do it first in a Youtube video. The instructions aren't much help with the actual assembly, but they are clear on the bed levelling and zeroing process. Careful to tighten the screws on the arms though, or they'll come undone part way through your first print! It's a little under the dimensions I guessed: approximately WxDxH: 340x300x560, excluding the spindle holder (which is easily removable). I'm planning to put it in a cabinet on the balcony. I think this IKEA Josef will be perfect. I'll have to cut some holes in it for ventilation, which I think I'll do using a drill powered nibbler. I assume the cabinet will arrive flat packed which should make it fairly easy to work on the panels. Rather than cut holes
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3D Printer ramblings

 I have a Prusa i3 mk2.5 in storage. I used to use it in my shed I used not to worry about it's harmful emissions: I just didn't share the space with it. I had, however, added an enclosure, and was planning to add a HEPA filter too it. Once it's in an enclosure, it's massive. Even if I had added the filter, there's no where to put it. I'd like a small printer that has an enclosure or is easy to enclose. I figure I could get by with 150x150x150 build area: I was rarely patient enough to wait for my i3 to print bigger models. 200x200x200 would probably actually replace my current printer, so that would be a bonus. Not many printers have HEPA filters, which is really a shame. It seems just to be the result of a misconception about HEPA filters, and about filtration in general. Read this . E.g. I was looking at a used Lulzbot mini, and there are ready made enclosure s for it, however . In this particular case, it's no big deal: opportunities to buy a Lulzbot min
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Drill guide/stand

 I'm sure I've mentioned JSK-koubou  before. There's a tool he uses in lots of videos: It's a magnetic drill guide . I've never seen him use the magnetic function: he just clamps it to things to drill accurately, and it's superbly versatile. I don't have access to a shop of any sort at the moment, but I do have hand tools. It might be possible to make something like this Drill Press . maybe I can mash up these two things: I want to use a cordless drill without a collar, so I bought this chuck and spindle from Banggood  like the one used in the drill guide. I also bought some draw runners . These are a bit stiff, but they have no play at all, so it must be possible to produce something very precise and robust with them. I'm really surprised. Everything else will be made of 12mm plywood. Most of the assembly techniques will come from the drill press, including the double sided tape, etc. I want the drill guide because it's something I can conveniently
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Tiny Quadcopter (Part 4)

I've got the two radios talking to each other, and I've written a trivial implementation of sumd, which I haven't tested yet. See https://github.com/davidji/rust-rc A bunch more stuff has arrived in the post, including: Tiny form factor NRF24L01+ modules, w/o LNA Combined Arduino Nano NRF24L01+ boards This is rather quicker than I expected, which makes me regret cobbling together an STM32F4 board, NRF24L01+ with LNA and buck boost converter. The trouble with the STM32F4 board is it's too long for the quadcopter frame. More annoyingly, so is the combined Arduino board. It's probably time to go back to the Arduino pro micro with Tiny NRF24L01+ module and LDO regulator. It would be interesting to know, when considering the energy efficiency of various things I might put on a quadcopter, how much power the quadcopter needs to hover and how that relates to it's weight. It's pretty likely that almost all the power goes to hovering, and weight is very
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Tiny Quadcopter (Part 3)

I though the regulator on board the micro-controller would not be enough for the range extender, but it can actually output 300mA, so I think it is. Here's a bunch of reference information on the board , which may be useful in any case. The regulator is an AP7343 . It's drop-out voltage is only 310mV, but that still means I'd need 3.6V or so to still have regulated power, which is more than the LIPO will have at the end of it's discharge. At least when I plug in the USB, it can power the radio for testing. What can I do otherwise? The radio and the micro-controller can run on a voltage as low as 2V. I have adjustable regulators on hand, but they don't help much, because they have much higher drop out voltages. I have 2 Pololu S7V8F3 s  somewhere . They would be ideal if I could find them - they are pretty much designed for my purpose. What I actually found is an S7V8A, which I guess will do... Although I have the challenge of adjusting it before soldering it
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Tiny Quadcopter (Part 2)

See previous post . Programming via DFU worked fine, and USB serial also worked, after I added stm32f411 to the list of supported devices in stm32f4xx_hal . I should just check that serial echo example works and submit a pull request: so far I've only tried printing messages. This means I can definitely use my STM32F411 board without soldering any headers onto it, which keeps it small and lite. I've updated my project to use that board for the receiver, and a STM32F103 black pill for the transmitter. I now have a dilemma re NRF24L01+ boards. There are a few variables: With, or without RFX2401 range extender. The main issue is they draw 90mA during TX. The on board 3.3V regulator on the micro-controller board can't handle that and neither can the 5V output of the flight controller, so I would have to add a dedicated regulator, powered directly from the battery. It also draws 8mA in receive mode. Standard header vs 1.27mm edge connectors: the boards with the latt
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